Goal: The program goal is to train predoctoral and postdoctoral biostatisticians in statistical theory and methods as applied to environmental health sciences (EHS). This aim is addressed by an integrated collaboration between biostatisticians and toxicologists to provide: supervision by biostatistician with extensive experience in the development of statistical methodology; interaction with researchers with extensive experience in human and animal studies; practical experience in the applications of statistical methodology to problems in toxicology by participating in consulting projects and attending colloquia; mentoring of trainees to assist in developing independent academic careers. Training: This training program is a collaboration between the Department of Biostatistics and Computational Biology and the Environmental Health Sciences Center. The Department of Biostatistics & Computational Biology offers a Ph.D. degree in Statistics with an option in Biostatistics. The Department, created to foster biostatistical research and collaboration with researchers in the Medical Center, provides the administrative leadership and the critical link with the toxicologists. Trainees will be matched with a biostatistician as primary preceptor and a toxicologist as a secondary cosponsor. The EHS Biostatistics Training Grant Committee will review the progress of the trainees and the program. Trainees: Predoctoral trainees will have completed a baccalaureate degree with a major in mathematics, statistics or a science major with a strong minor in mathematics or statistics. Selection is based on academic record, GRE scores, and recommendations. Predoctoral trainees must fulfill the standard requirements for the Ph.D. degree in statistics plus additional courses in biostatistics, epidemiology and toxicology. Two predoctoral four-year awards will be granted. Postdoctoral trainees must have completed a Ph.D. in statistics, mathematics or a related discipline, or a Ph.D. in toxicology. Each postdoctoral trainee will enroll in appropriate courses, attend seminars, and work with faculty mentors on biostatistical research and specific toxicology related projects. Two postdoctoral traineeships are awarded to establish an alternating two-year program.